This invention lies in the field of gravity clarifiers for separating biological solids or sludge and other flocculent solid from water, by gravity settling. More particularly, it concerns a type of gravity clarifier in which the liquid flow patterns within the clarifier are derived from the energy of the influent liquid mixture, which flows tangentially into the circular tank. It further includes the feature of an inverted conical shell through which the outflowing liquid rises through the open bottom of the conical shell, with a constantly decreasing upward velocity, thus permitting the entrained solid matter to be released, and to agglomerate, and to fall as sludge to the bottom of the tank.
In the prior art various means have been devised for settling the solids out of a liquid mixture including the use of centrifugal force as in the hydrocyclones. The high velocity liquid flow in such systems however are damaging to the character of the floc normally present in the biological material, which comes in with the influent liquid. If the floc is fragile, a much lower velocity and more streamline flow of liquid mixture is required and conditions which promote flocculation are desirable, which are provided by the system of this invention.